I just receive an email from Anova support. They are sending me a replacement unit. I’m not required to send the existing one back; instead, I was asked to take it to an e-waste centre and to provide a photo of the receipt.
I have no idea whether they hand out receipts for something as small as this; it’s a giant government waste facility. I guess I can always take a selfie with me and my old Anova in front of giant pile of electronics gear that’s about to be scrapped 
Full marks for Anova customer support! That was a very fast and unbureaucratic way of addressing my problem.
Fingers crossed that the next one won’t smell…